0620_m16_qp_32
A paper of Chemistry, 0620
Questions:
7
Year:
2016
Paper:
3
Variant:
2
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1
The diagram shows part of the Periodic Table. I Li Ti Cr Fe Cu Zn C N O F Ne Ar Kr Xe Br I Si Ge Sn Pb Al Cl II III IV V VI VII VIII Answer the following questions using only the elements in the diagram. Each element may be used once, more than once or not at all. Which element forms 78% of the air, has an oxide which is a product of respiration, is used to make food containers because of its resistance to corrosion, forms an ion of type X3+, forms an ion whose aqueous solution forms a light blue precipitate on addition of a few drops of aqueous ammonia? Calcium is an element with several naturally-occurring isotopes. What is the meaning of the term element ? Two of the isotopes of calcium are Ca and Ca . Complete the table to show the number of protons, neutrons and electrons in one atom of each of these isotopes. Ca Ca number of protons number of neutrons number of electrons Determine the number of electrons in one calcium ion, Ca2+.
2. Atoms, elements and compounds  →  2.2. Atomic structure and the Periodic Table
2. Atoms, elements and compounds  →  2.3. Isotopes
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2
Molten potassium bromide can be electrolysed using the apparatus shown. + – graphite electrodes molten potassium bromide Predict the products of this electrolysis at the positive electrode , negative electrode . Explain why graphite electrodes are used in this electrolysis. Give one other use of graphite. When chlorine is bubbled through an aqueous solution of potassium bromide, the solution turns red-brown in colour. Which substance causes the red-brown colour? Describe what you would observe when an aqueous solution of potassium bromide is added to an acidified aqueous solution of silver nitrate. Silver nitrate decomposes when heated. One of the products is nitrogen dioxide. State one adverse effect of nitrogen dioxide on health.
4. Electrochemistry  →  4.1. Electrolysis
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3
Many metals react with either cold water or steam. Describe the reaction of sodium with cold water, and iron with steam. In your answer describe • the products formed, • any observations that can be made. Iron reacts with hydrochloric acid. Fe+ 2HCl → FeCl 2+ H2Describe a practical method to investigate the rate of this reaction. You may draw a labelled diagram. The experiment in was repeated using different sized pieces of iron. All other conditions remained the same. The sizes of the pieces of iron were • large pieces, • small pieces, • iron powder. Complete the table below by writing the sizes of the pieces in the first column. sizes of the pieces of iron rate of reaction in cm3 hydrogen / min The graph shows the effect of temperature on the rate of the reaction of hydrochloric acid with iron. temperature / °C rate of reaction in cm3 hydrogen / min Describe the effect of temperature on the rate of this reaction. Determine the rate of reaction at 60 °C. cm3 hydrogen / min Describe how the concentration of hydrochloric acid affects the rate of its reaction with iron.
6. Chemical reactions  →  6.2. Rate of reaction
9. Metals  →  9.4. Reactivity series
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4
The structures of sodium chloride and nitrogen are shown below. Na+ Cl – Na+ Na+ Cl – Cl – Na+ Na+ Cl – Cl – Na+ Cl – Na+ Cl – Na+ Cl – sodium chloride nitrogen N N N N N N N N Describe the structure and bonding of these two substances and the differences in • their volatility, • their electrical conductivity. Ammonia is manufactured by reacting nitrogen with hydrogen using a catalyst. What is the purpose of the catalyst? Complete the chemical equation for this reaction. N2 + H2 → NH3 Complete the electronic structure of a molecule of ammonia. Show only the outer electrons. N H H H Ammonia reacts with copper(oxide. 2NH3 + 3CuO → 3Cu + 3H2O + N2 Which compound is reduced in this reaction? Explain your answer.
2. Atoms, elements and compounds  →  2.5. Simple molecules and covalent bonds
9. Metals  →  9.4. Reactivity series
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5
The table shows some properties of cobalt, copper, magnesium and tin. metal relative heat conduction density in g / cm3 melting point / °C relative strength cobalt 1.00 8.90 55.0 copper 3.85 8.92 32.0 magnesium 1.50 1.74 1.5 tin 0.64 7.28 1.0 Answer the questions using the information shown in the table. Which metal is the best to use for the base of a pan for cooking food? Use information in the table to give reasons for your answer. Which two metals in the table are transition elements? Use information in the table to give reasons for your answer. Which metal in the table is most likely to be used in an alloy for aircraft bodies? Use information in the table to give reasons for your answer. Some observations about the reactions of the four metals with hydrochloric acid are shown in the table. metal observations cobalt Bubbles formed very slowly. copper No bubbles formed. magnesium Many bubbles formed very rapidly. tin A steady stream of bubbles formed. Use the information in the table to put these metals in order of their reactivity with hydrochloric acid. least reactive most reactive Crystals of hydrated cobalt(sulfate, CoSO4.7H2O, can be made by reacting dilute sulfuric acid with insoluble cobalt carbonate. Describe how you could prepare a pure dry sample of cobalt(sulfate crystals from dilute sulfuric acid and cobalt(carbonate. When heated, hydrated cobalt(sulfate forms an anhydrous salt in a reversible reaction. Complete the equation for this reaction by inserting the sign for a reversible reaction in the box. CoSO4.7H2O hydrated cobalt(sulfate pale red CoSO4 anhydrous cobalt(sulfate dark blue + 7H2O Suggest how you could use this reaction to test for the presence of water.
9. Metals  →  9.4. Reactivity series
6. Chemical reactions  →  6.3. Reversible reactions and equilibrium
9. Metals  →  9.1. Properties of metals
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6
Citric acid is found in lemon juice. Citric acid shows typical acidic properties. Describe how you could determine the pH of a solution of lemon juice using Universal Indicator. The structure of citric acid is shown below. C C C C H H C O O H O O O O H H H H O C H On the diagram, draw a ring around a carboxylic acid functional group. State the name of one other carboxylic acid. Calcium citrate can be prepared by neutralising aqueous citric acid with excess calcium carbonate. Complete the word equation for this reaction. citric acid + calcium carbonate → calcium citrate + + Suggest how you could separate the excess calcium carbonate from the rest of the solution. The energy level diagram for the reaction of citric acid with sodium hydrogen carbonate is shown below. energy reactants products Is this reaction exothermic or endothermic? Give a reason for your answer. Both citric acid and ethanol can be manufactured by fermentation. Complete the chemical equation for the fermentation of glucose to form ethanol. C6H12O6 → C2H5OH + CO2 State two conditions needed for fermentation. Complete the table below and calculate the relative molecular mass of glucose. type of atom number of atoms relative atomic mass carbon 6 × 12 = 72 hydrogen oxygen relative molecular mass =
11. Organic chemistry  →  11.7. Carboxylic acids
7. Acids, bases and salts  →  7.1. The characteristic properties of acids and bases
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7
Rhenium is a metal. Describe three physical properties of rhenium. The structure of a rhenium chloride molecule is shown. Cl Cl Cl Cl Re Re Re Cl Cl Cl Cl Cl Determine the simplest formula for this chloride of rhenium. Rhenium oxide is a yellow solid which undergoes sublimation at a low temperature. What is the meaning of the term sublimation? Rhenium oxide reacts with water to form perrhenic acid. Perrhenic acid is strongly acidic. Which one of the following pH values represents an acidic solution? Draw a ring around the correct answer. pH 2 pH 7 pH 9 pH 14 Perrhenic acid reacts with potassium hydroxide. Complete the word equation for this reaction. perrhenic acid + potassium hydroxide → potassium perrhenate + Which one of the following compounds will react with perrhenic acid? Tick one box. ethane hydrochloric acid potassium carbonate sodium chloride Potassium perrhenate has a similar formula to potassium manganate(. Potassium manganate(decomposes to give off oxygen. Describe a test for oxygen. test result
7. Acids, bases and salts  →  7.1. The characteristic properties of acids and bases
9. Metals  →  9.4. Reactivity series
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